Important Safety Info | TIKOSYN® (dofetilide)


To decrease the chance of your getting a different type of dangerous abnormal heartbeat, TIKOSYN treatment must be started or re-started while you are in the hospital. Feeling faint, dizziness/lightheadedness, or having fast heartbeats are symptoms of this abnormal heartbeat. Call your doctor or emergency room as soon as possible if you have any of these symptoms.

While in the hospital, your kidney function and heart rhythm will be monitored for a minimum of 3 days. This helps the doctor to choose the right TIKOSYN dose for you.

Do not take TIKOSYN if you have congenital or acquired long QT syndrome (a disorder of the heartbeat which may be present from birth, or it may be acquired as a result of certain medical conditions or from taking certain medications. People with long QT syndrome may have symptoms including an unusually rapid heartbeat, fainting, and seizures. Sudden cardiac death may also result from long QT syndrome); have serious kidney problems or are on kidney dialysis; are taking certain other medicines, including cimetidine (Tagamet®, Tagamet HB®), verapamil (Calan®, Calan SR®, Covera-HS®, Isoptin®, Isoptin SR®, Verelan®, Verelan PM®), ketoconazole (Nizoral®), trimethoprim alone (Proloprim®, Trimpex®), the combination of trimethoprim and sulfamethoxazole (Bactrim®, Septra®), prochlorperazine (Compazine®), megestrol (Megace®), dolutegravir (Tivicay®) or hydrochlorothiazide alone or in combination with other medicines (such as Esidrix®, Ezide®, Hydrodiuril®, Hydro-Par®, Microzide®, or Oretic®); or are allergic to dofetilide or other ingredients in TIKOSYN.

The most common side effects of TIKOSYN are headache, chest pain, and dizziness. TIKOSYN can also cause other side effects. If you are concerned about these or any other side effects, ask your doctor.

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TIKOSYN is a medicine for highly symptomatic atrial fibrillation or atrial flutter (irregular heartbeats). TIKOSYN may help by converting the irregular heartbeats to normal rhythm. It may also help by keeping the normal rhythm for a longer period of time. It has not been shown to work on certain types of irregular heartbeats that may come and go on their own.

Please see Full Prescribing Information, including BOXED WARNING and Medication Guide.


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